i) Field of the Invention
The present invention relates to the use of a pressure regulator in conjunction with a breathing assistance apparatus, particularly though not solely, for regulating the pressure of gases supplied to a patient from a humidified Positive End Expiratory Pressure (PEEP) apparatus.
ii) Summary of the Prior Art
The use of a medical apparatus to facilitate breathing is well known in the art. The apparatus may take the form of a simple oxygen mask or tent which supplies oxygen at slightly above atmospheric pressure. Such devices merely assist a person to breath and work with the person""s lungs.
Ventilators which operate at high frequency have been suggested in the past. There are two types of high frequency ventilators known in the art. One type, as exemplified by U.S. Pat. No. 2,918,917 (Emerson), employs a reciprocating diaphragm to vibrate a column of gas supplied to a subject. The vibration is in addition to the subject""s respiration, natural or artificial, and at a much more rapid rate, for example, from 100 to more than 1500 vibrations per minute. The Emerson apparatus is primarily designed to vibrate the patient""s airway and organs associated therewith, although Emerson also recognized that high frequency vibration causes the gas to diffuse more rapidly within the airway and therefore aids the breathing function. However, the Emerson is incapable of supporting the patient""s full ventilation and must be used in conjunction with the patient""s spontaneous breathing or with another apparatus which produces artificially induced inhalation and exhalation.
The second type of high frequency ventilator is the jet pulse ventilator as exemplified in U.S. Pat. No. 4,265,237 (Schwanbom et al.). The Schwanbom et al. ventilator produces high frequency, high pressure pulses of air which are capable of fully ventilating a patient. The respiration pulse enters with a pressure of 0.2 bar to 2.7 bar. This pressure is sufficient to expand the lungs during inspiration. Expiration is caused by the natural compliance of the lungs after the jet of air is stopped. Accordingly, it can be see that Schwanbom et al must rely on the compliance of the lungs in order to fully ventilate the patient. If the lung compliance is low, greater pressure must be used. Schwanbom et al also supply a source of lower pressure gas for spontaneous breathing by the patient. While such jet pulse ventilators are useful for some applications, they are not generally applicable and their use is limited mostly to experimental work.
An improvement on these types is disclosed in U.S. Pat. No. 4,821,709 (Jensen) a which provides high frequency oscillations in the gases supplied to a patient using a flexible diaphragm. Jensen provides a more practical method of ventilating a patient without spontaneous breathing of the patient, or the need for a separate ventilator. U.S. Pat. No. 4,646,733 (Strot et al.) proposes an apparatus for producing high frequency oscillations in gases supplied to a patient using a valve controlling the exhaled gases.
It would be desirable to have a simple system for providing high frequency pressure oscillations for spontaneously breathing patients particularly for non invasive forms of support, where the means level of gases provided to the patient can be adjusted.
It is an object of the present invention to provide a pressure regulator which goes some way to overcoming the above-mentioned disadvantages, or which will at least provide the healthcare industry with a useful choice.
Accordingly, in a first aspect, the present invention consists in a pressure regulating device for use with a breathing assistance apparatus which conveys inhalatory gas to, and removes exhalatory gas from a patient requiring breathing assistance, comprising:
a container which in use includes a body of liquid, having a substantially constant level in use,
a terminal conduit including proximate and distal ends, said proximate end adapted for connection to a breathing assistance apparatus and in use accepting exhalatory gas therefrom, and said distal end submerged in said body of liquid,
such that in use the mean pressure of said gas supplied to a patient is adjusted by the level to which said distal end is submerged in said body of liquid.
In a second aspect, the present invention consists in a breathing assistance apparatus for supplying gas to a patient to assist said patient""s breathing a gas supply adapted to supply gas to said patient, an interface including a plurality of ports adapted to deliver said gas to said patient, an inhalatory conduit for conveying said gas from said gas supply to said interface, exhalatory conduit for conveying said patient""s exhalations from said interface
a container which in use includes a body of liquid, and
a terminal conduit including proximate and distal ends, said proximate end adapted for connection to said exhalatory conduit and in use accepting exhalatory gas therefrom, and said distal end submerged in said body of liquid,
such that in use said patient is delivered a substantially constant mean pressure, said mean pressure adjusted by the level to which said distal end is submerged in said body of water.
In a third aspect, the present invention consists in a pressure regulating device for use with a breathing assistance apparatus which conveys inhalatory gas to, and removes exhalatory gas from a patient requiring breathing assistance, comprising:
a container which in use includes a body of liquid having substantially constant level in use, and
a terminal conduit including proximate and distal ends, said proximate end adapted for connection to a breathing assistance apparatus and accepting exhalatory gas therefrom, and said distal end submerged in said body of liquid,
such that in use the resultant bubbling occurring in said body of liquid produces relatively small controlled perturbations in the pressure of gas supplied to a patient.
To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.